There are portable terminal apparatuses such as a mobile phone, a PHS (Personal Handyphone System), and a PDA (Personal Data Assistance, Personal Digital Assistants) on which the PPT (Push to Talk) communication function is installed. In the PTT communication, a right to talk is given to one user, and communication service (half-duplex speech dialog service) for one or more persons (one to one or one to a group) is provided.
As a wireless phone with the PTT communication function, Patent Document 1 discloses a wireless PTT Internet broadcast in which a wireless phone digitizes the voice of a user in response to the depression of a PTT button and sends the digitized voice, in data mode, to a base station. The base station transmits the digitized voice to the other wireless phonies, and the other wireless phones convert the received digitized voice back to voices according to the recognition result of voice frames. Patent Document 2 discloses a configuration in which, when a PTT mode is set, the speech recognition operation is performed in response to the depression of a button switch and a PTT dictionary is used for matching processing. As management of the right to talk, Patent Document 3 discloses a configuration in which the right to talk is managed by sending talk permission signal only to one wireless terminal station, which is one of multiple wireless terminal stations participating in group conversation, by means of wireless terminal station management means.    Patent Publication 1: JP2002-536928A    Patent Publication 2: JP2001-042894A    Patent Publication 3: JP Patent No. 2590753